The present disclosure generally relates to sensors and converters, and more particularly to methods and systems for directly coupling a capacitive sensor to a delta-sigma analog-to-digital converter.
Petrochemical products such as oil and gas are ubiquitous in society and can be found in everything from gasoline to children's toys. Because of this, the demand for oil and gas remains high. In order to meet this high demand, it is important to locate oil and gas reserves in the Earth. Scientists and engineers conduct “surveys” utilizing, among other things, seismic and other wave exploration techniques to find oil and gas reservoirs within the Earth. These seismic exploration techniques often include emitting seismic energy into the Earth with a seismic energy source (e.g., air guns, vibrators, dynamite, etc.), and monitoring the Earth's response to the seismic source with one or more receivers in order to create an image of the subsurface of the Earth.
The response of the Earth to the seismic energy is typically recorded at a plurality of receivers that may be, for example, towed behind an acquisition vessel in a marine survey, or positioned across a large swath of land in a land survey. Each receiver may include one or more sensors, including a particle motion sensor, a pressure sensor, or both a particle motion sensor and a pressure sensor in proximity to one another. The particle motion sensor may be, for example, a three-component geophone or accelerometer that records vectorial measurements of a reflected seismic wavefield. The pressure sensor may be, for example, a hydrophone that records scalar pressure measurements of the reflected seismic wavefield. By observing the reflected seismic wavefield detected by the receivers during the survey, geophysical data pertaining to the reflected signals may be acquired and this data may be used to form an image indicative of the subsurface near the survey location.
One type of particle motion sensor that may be used in a seismic survey is a capacitive piezoelectric sensor. Such a capacitive piezoelectric sensor may have a source impedance that is primarily capacitive, which may make it difficult to access a voltage on the sensor that is indicative of the motion sensed by the sensor.